Process for manufacturing a boat hull

ABSTRACT

A closed molded system uses reaction injection molding for producing large vessels with hulls, such as a boat hull or large containers. Inserts are used to create a cavity to produce a core. Thereafter the inserts are removed and the same mold is then used to make the other layers of the hull. Closed molding provides controlling the shape of both the outside and the inside of the part. Filler inserts can be used to section off the molds in order to allow for separate core densities.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.60/657,645, filed Mar. 1, 2005.

FIELD OF THE INVENTION

The present invention relates to a process of manufacturing a boat hull,deck, or other large laminate parts. The process utilizes a closedmolded system for producing a unitary laminate part, whereby a pre-coreand stringers are integrally molded during a reaction injection moldingprocess.

BACKGROUND AND SUMMARY OF THE INVENTION

Large fiberglass parts, such as boat hulls and large containers usestringers and bulkheads inside the part to increase their strength. Theribs or stringers create sections or flat parts between them. These flatparts are where one of the improvements arises. In an attempt toincrease the strength of the laminate a closed mold system has beenutilized to optimize strength through thickness and shape.

Traditionally, a fiberglass boat hull is fabricated using a one-sidedopen mold where layers of laminate are applied on top of one another.The first layer is generally the outside layer made of a gel coat andsubsequent fiberglass mat and resin layers are put down thereafter. Inthe middle of the laminate a core of wood, honeycomb, foam, etc. isapplied. A final layer of fiberglass and resin is then applied to thecore. Stringers, bulkheads and other structures are fabricated later.

There are many disadvantages of the traditional open mold hand lay upprocess. For example, it takes many labor hours to fabricate a hullusing the traditional process because each layer is applied by hand.Further, because the mold is open, workers are often exposed to toxicfumes from the resin. Also, the old method creates voids in the laminatewhich can require post lamination repair. Moreover, the traditionalmethod only molds one side of the part at a time, which decreases thequality of the part. Moreover, the old method is not very reproducible,which decreases consistency of the final hull thus making no two partsthe same. Further, the old method results in an unfinished interiorsurface, such as the headliner or engine compartment, which is laborintensive to later finish. Accordingly, it is therefore desirable toovercome the aforementioned problems with a new, less expensive, fasterproducing, higher quality, more repeatable process for molding a hullfor a vessel.

One aspect of the present invention uses a two-sided closed mold methodof manufacturing a large hull for a boat, container, etc. With closedmolding, the shape of both the outside and inside of the part can becontrolled. Another aspect of the invention has the shape of the flatsof the laminate in a concave manner by which the square or rectangleflat sections of the inside of the part have a slight dish shape tothem. An additional aspect of the invention has the stringer, bulkhead,and gusset system built collectively as a unitary structure into thehull.

One form of the present invention creates a hull having one or bothsides of the laminate that are dish shaped. The dish shape will enhancethe strength of the laminate without increasing the core thickness ormatt and resin thickness. If only one side of the laminate is dishedthen it would actually decrease the amount of the core material in thelaminate. If both sides of the core are dish shaped, meaning one side isconcave and one side is convex, then the core would be the samethickness assuming both convex and concave shapes are consistent in sizeand shape. This dish shaped portion of the hull reacts against thepressure that is being applied to the bottom of the boat by the waves,thus making the laminate stronger by shape.

A second form of the present invention provides an improved boat hulldesign with an integrally molded stringer, bulkhead, and gusset systemfor creating a one piece unitary structure. The resulting boat hull isstronger, takes less time to manufacture, has improved fit and finishfrom the inside of the boat hull, and eliminates the need for finishingthe engine compartment, a typical additional step in the traditionalmethod of manufacturing a hull.

A third form of the present invention includes a method of manufacturinga boat hull using a two part closed molding process comprising the stepsof building hull A and B molds, said molds having a top, bottom and aside, installing inserts into their respective molds, introducing thehull bottom and hull sides with material, and venting excess coringagent out of the top of the mold to allow for expansion. Next hull Bmold and hull A mold are separated, sheeting hull bottom core withmaterial, pulling stringer, bulkhead and engine compartment inserts,introducing core agent, pulling core and draping core with fiberglassmat. Pulling remaining inserts from molds, spraying molds withprotective agent, inserting core into mold, closing molds, injectingmaterial and releasing part.

A forth form of the invention includes a boat hull constructed using aclosed mold processes, comprising a first layer of composite material, acore layer adjacent to the first layer, and a second layer of compositematerial.

The novel process has the capability of not only producing a boat hullor deck, but other large parts as well. Other examples include fuselageand plane parts for the aerospace industry, rocket housings and shellsfor the military and defense industry, containers for the storage,transportation and aggregate business, trailer shells for the truck andtrailer business and housing units for the housing industry. Any largeitem which can be produced in a closed molded system needing a core forit's laminate can use this invention.

Further areas of applicability of the present invention will becomeapparent from the detailed description provided hereinafter. It shouldbe understood that the detailed description and specific examples, whileindicating the preferred embodiment of the invention, are intended forpurposes of illustration only and are not intended to limit the scope ofthe invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from thedetailed description and the accompanying drawings, wherein:

FIG. 1 illustrates a cross section of a boat hull of the presentinvention;

FIGS. 2 a-2 c illustrate a flow diagram of the steps in the method formanufacturing the present invention; and

FIG. 3 is a cross sectional view of the boat hull after it has beenconstructed.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following description of the preferred embodiment(s) is merelyexemplary in nature and is in no way intended to limit the invention,its application, or uses. For discussion purposes only, a boat hullconstruction will be described.

With reference to FIG. 1, an improved boat hull mold 10 is illustratedwith the configuration of the remainder of the boat 12 shown in phantom.The boat hull mold 10 utilizes a unique closed molded system thatemploys an exterior hull mold 14, an exterior insert 16, a core 18, aninterior insert 20, and an interior hull mold 22. Stringer inserts 24,26, and 28, may be integral or located adjacent to the core 18 and arelocated within the engine compartment 30 and throughout the hull 116.The exterior mold 14 sits on a base 32 during the molding process. Abulkhead 34 and gusset system 36 can also be molded integrally in thehull mold 10 in order to create a single unitary design.

The interior hull mold 22 forms the inside of the hull mold 10 and has astringer, bulkhead and gusset system integrally built into thestructure. This design allows the manufacturer to include the stringer,bulkhead and gusset system built into the structure as one compositepiece. Traditionally, boats have their stringer, bulkhead and gussetsystems added after the hull laminate is done. The benefits of includingthe stringer, bulkhead and gusset components into the hull include 1) astronger design because the components are an integral part of the hull,not a later addition; 2) It takes less time to build the components intothe boat during the closed molding process; 3) the inside of the hullwill have a bright, beautiful finish, much like the outside of the part;4) the engine compartment comes out of the mold already done thuseliminating the need for further finishing; and 5) the inside of thehull forward which makes up the interior space of the boat is finishedreducing manufacturing cost.

The interior insert 20 is designed to take up the space that willeventually be the resin, or glue, and mat layer that makes up the insideof the hull laminate. Because each manufacture may use a differentlaminate depending on demand of physical properties of the part, theinsert thickness will vary from mold to mold. The insert 20 allows themanufacture to produce a three dimensional core 18 utilizing the samemold 14 and 22 as the actual part uses. The core 18 must be thinner thanthe actual part because the manufacture adds resin and mat to the core.Without the inserts 16 and 20, the manufacture would have to produce aseparate mold for the core, which would increase the cost of the moldsand take up valuable floor space. This invention contemplates amanufacturer producing multiple molds for the part and the coreseparately if they decide to do so. However, the most economical way toproduce the part is with the utilization of the inserts 16 and 20.

The stringer inserts 24, 26, and 28 and bulkhead inserts and core can bemade of any material including, but not limited to, foam, fiberglass,plastic, or laminate and are designed to fill the stringers to allow thehull bottom 38 and hull sides 40 to be molded alone or separate from thestringers 24, 26, 28 and bulkheads 34. The stringers often use adifferent density of foam than the bottom of the boat. This allows thebuilder to make the stringers separate from the hull bottom and sides.The benefit is to have a balanced laminate. If the stringers, bulkheadsand gussets were all part of the hull core, there would not be acomplete laminate sandwich. The sandwich aids in laminate strength. Itis preferred to have the same amount of mat and resin on both sides ofthe core 18. If the stringers, bulkheads and gussets are attached to thehull core 18, there wouldn't be an opportunity to get mat underneath thestringers, bulkheads and gussets. This would potentially cause a weakpoint in the laminate that could jeopardize the strength of the product.

It is contemplated that the stringer inserts 24, 26, 28 could beeliminated and to mold the stringer, bulkhead and gusset systems intothe hull core 18 directly. There may be products that don't demand suchcompletely balanced laminates. In which case it would save time andmoney to include the stringer, bulkhead and gusset system into the core18 and make them one piece.

The hull core 18 is what the laminate is built around. It is the firstpart in the lamination process to be built. The hull core 18 will startas an empty cavity in the shape of a boat hull. That cavity will befilled with core material to produce a three dimensional part which willultimately be draped with mat and reinserted into the molds, less theinserts, and injected, poured, sprayed or rolled by hand. This will thenproduce the hull part. The foaming core agent will be vented out of themolds to allow for expansion and density control. The vents will be ableto be open and closed utilizing a ball valve type vent. Once the core 18is cured or hardened the vents can be opened and the hardened core canbe cleared by use of a stop drill. This drill is slightly smallerdiameter of the vent itself and will have a built-in stop to allow fordepth control. This will also allow the builder to blow air into themold to help release it from the mold.

The exterior insert 16 is designed to take up the space that willeventually be the resin and mat layer that makes up the outside 42 ofthe hull laminate. Because each manufacture may use a different laminatedepending on demand of physical properties of the laminate, the insertthickness will vary from mold to mold. The exterior hull mold insert 16will ultimately be the mat and resin layer for the bottom of the boatpart.

There are two molds for each part. The interior hull mold 22 that makesthe inside of the hull part. The exterior hull mold 14 makes up theoutside of the hull part. The following is a brief description of how amold is made. A CAD or computer-generated drawing is made, that drawingis downloaded then into a CNC machine. The CNC machine mechanicallyshapes a block (foam, wood, plastic, etc.) into the plug part. This plugis used to make a duplicate, in female form, of the part to be produced.The female form is the master mold. It will be appreciated that the mold14 could be produced from a CNC type machine, eliminating the forming ofthe plug and going straight to the mold. Molds made of metals includingaluminum, currently utilized by the automotive industry, are madewithout the use of plugs or models. This invention contemplates thehand-making or lofting the hull plug although most manufacturers nowutilize computers and robots.

With reference to FIGS. 2 a-2 c, the steps for manufacturing a boat hullof the present invention will be described.

The first step requires building all necessary molds 44 which in thisinstance includes exterior mold 14 and interior mold 22. The next steprequires building inserts 46 that are to be later used inside the mold.These include exterior insert 16, interior insert 20, stringer inserts24, 26, and 28, bulk head inserts, and transom inserts. Now that themolds and inserts have been created, the manufacturer can begin thespecific process of making a hull.

The next step requires locating the inserts into the molds 48. The nextstep 50 requires blowing, inserting, injecting, or pouring core materialinto the hull bottom insides. Thereafter the venting step 52 allowsexcess coring material to come out of the mold to allow for expansion.The drilling step 54 takes place next where the vents are drilled with astop drill in order to clear excess core material and to allow for apassageway for air to be blown into the core thereafter. The next step56 requires blowing air into the vents in order to aid in the release ofthe core from the molds. Separating molds 58 is the next step whichopens up the mold and exposes the core 18 to be later processed.

Once the molds are open, the hull core is sheeted 60 with material inorder to separate the hull core from stringer and bulk head. It will beappreciated that this step is optional and is done only if the builderdesires a separation of the hull core from the stringer and bulk headcore. The next step requires removing the stringer and bulkhead inserts62 from the molds. The next step is optional which includes removingengine compartment and transom inserts 64. This step 64 is onlyperformed if the builder desires separation of the forward stringer andthe bulk-head core from the engine compartment stringer and the transomcore. The stringer and bulkhead inserts may be joined as one piece tothe engine compartment stringers and transom inserts.

The next step 66 is also optional which includes sheeting or separatingthe engine compartment stringers from the engine compartment bulkheads.This optional step 66 is done only if the builder desires a differentdensity core agent to be used in the engine compartment versus theforward stringers and bulkheads. Thus, the present design provides for aflexible construction that provides for a hull having differentperformance characteristics. The next step 68 requires joining theinterior and exterior molds after the sheeting and removal of insertsteps have been completed.

With reference to FIG. 2 b, the method of manufacturing a hull iscontinued. Once the molds have been closed, the next step 70 requiresblowing, inserting, injecting, or pouring coring agent into allstringer, bulkhead and transom cavities. At this point, the builder mayuse a different density core material so as to meet the needs of thepredetermined laminate construction. This step allows for flexibility ofthe hull design. The next step 72 allows for venting excess coring agentout of the mold to allow for expansion of the agent within the cavities.Once the coring agent has expanded and cured, the next step requiresdrilling vents 74 with a drill in order to clear excess core material soas to create an air passageway. Once the vents have been drilled out,the next step 76 requires blowing air into the vents in order to helprelease the core. The next step 78 requires separating the molds so asto provide access to the cavity. Once the molds are separated, the nextstep 80 requires removing all the cores from the molds, and thenstripping the sheeting material from the hull core 82. After that hasbeen completed, there is an optional step 84 wherein the manufacturercan cut the engine compartment stringer core from the transom core inthe jig. This allows the builder to have a balanced laminate on transomif so desired.

The next step requires placing cores 86 into a proper position for matdraping. Thereafter, the step of draping the outside hull core 88 isperformed where glue is used if so needed. Thereafter, hull mold insert16 is removed 90 and then the interior insert 20 is removed at step 92.Thereafter draping the hull core 94 is performed.

With reference to FIG. 2 c, the method of manufacturing a hull isfurther illustrated. The next step 96 requires shooting, spraying,rolling, or applying the exterior hull mold 14 with a protectivematerial such as gel coat or polyurea. It will be appreciated that otherprotective material could be utilized. The next step 98 requiresshooting, spraying, or rolling the interior hull mold 22 with aprotective material as previously described. The next step 100 requiresshooting, spraying, rolling, or injecting resin or glue in order toprepare the hull core 18. It will be appreciated that this may be donewith the part in the molds and with the molds closed or open. The nextstep 102 requires closing and joining the molds together one last time.The next step 104 requires venting the excess resin or glue out of themold so as to allow for expansion of the material therein. The next step106 requires screwing or clamping the molds together to squeeze outexcess resin or glue, the benefit of which is to assist in eliminatingvoids in the final laminate structure. The part is then cured 108,wherein thereafter, vents are drilled 110 in order to clear excess resinor glue so as to create a passageway. The next step requires the blowingof air 112 into vents in order to help release the part. The final step114 is actually releasing the part from the molds. It will beappreciated that the above-referenced steps can be varied in order tocreate the invention.

With reference to FIG. 3, the resulting boat hull 116 is depicted thathas been made through using the steps outlined in FIG. 2 above. Thecomponents of the boat hull include an outer gel coat layer 118, anouter resin and mat layer 120, a central core 122, an inner resin matlayer 124, and an inner gel coat layer 126. A radius 128 is used withthe gusset 36 and becomes integral with the structure. It will beappreciated that the gusset 36 can be located at predetermined locationsthroughout the boat hull 116 so as to provide structural integrity. Alaminate layer 130 is positioned underneath the core 132 of the stringer134. Each stringer 134 has an exterior gel coat 136, a mat with resinlayer 138 and its own core 132. By placing the laminate layer 130between the core 132 and the core 122, the core 132 can be made ofdifferent material as so desired by the manufacturer.

Further illustrated in FIG. 3 is the concave shape portion 140 disposedbetween stringers that can be located systematically throughout thehull. It will be appreciated that the concave shape could be continuousthroughout the linear length of the hull. The concave shape is anintegral part of the hull and is created during the close moldingprocess. For illustrative purposes only, the concave shape 140 is onlyshown on the right side of the hull 116. The inner gel coat 126 a, innerresin and mat layer 124 a, and the core 122 a, take on this concaveshape which aids in the structural integrity of the hull. The outer gelcoat layer 118 and the outer resin and mat layer 120 preferably employ aflat configuration as illustrated. However, it will be appreciated thatthey too could be configured to take on a concave shape by changing theshape of the mold.

An alternate embodiment to the present closed molded system includesmodifying the stringers and bulkheads that form part of unitary hull.Typically, the ribs or stringers and bulkheads are glassed or glued intothe hull bottom where the transition from the stringer or bulkhead tothe hull bottom has no radius or very slight. The closed molding wouldallow for a predetermined radius to be added or built into the mold,which would increase the strength of the joint. It will also makecleaning easier and look more attractive.

1. A method of manufacturing a boat hull using a two part closed moldingprocess comprising the steps of: a. Building hull A and B molds, saidmolds having a top, bottom and a side; b. Installing all inserts intotheir respective molds; c. Introducing the hull bottom and hull sideswith material; d. Venting excess coring agent out of the top of the moldto allow for expansion; e. Separating hull B mold from hull A mold; f.Sheeting hull bottom core with material; g. Pulling stringer inserts andblowing core agent; h. Pulling core; i. Draping core with mat; j.Pulling remaining inserts from molds; k. Spraying molds with protectiveagent; l. insert core into mold; m. Closing molds and injectingmaterial; and n. Releasing part.
 2. The method of manufacturing a boathull as claimed in claim 1, wherein the boat hull is comprised of ribsthat are strengthened by contouring generally flat portions into adish-shape.
 3. The method of manufacturing a boat hull as claimed inclaim 1, further comprising the step of contouring stringers andbulkheads where they meet the hull bottom to strengthen a joint.
 4. Amethod of manufacturing a boat hull comprising the steps of: Providing ahull core, string bulkhead transom (SBT), molds A and B, hull mold A andB inserts; Pulling and curing hull core; Separating molds A and B;Removing string bulkhead transom; Sheeting hull B; Joining molds A andB; Coring and curing a SBT core; Separating molds A and B; Removing SBTcore; Removing hull core; Draping an outside of the hull core; Removingthe hull mold A insert; Removing the hull mold B insert; Draping aninside of the hull core; Shooting hull mold A with a plastic; Shootinghull mold B with a plastic; Fixing SBT to hull core and draping; Drapinghull core; Shooting and installing hull core into hull mold A; Shootinghull core top; Joining hull mold B and hull mold A; and Curing the boathull for a predetermined time period.
 5. The method of manufacturing aboat hull as claimed in claim 4, wherein a closed mold process is usedto make the hull.
 6. A boat hull constructed using a closed moldprocesses, comprising: a first layer of composite material; a core layeradjacent to the first layer; and a second layer of composite material.7. The boat hull as claimed in claim 6, wherein a RIM process is used.8. The boat hull as claimed in claim 6, further comprising an insertlocated adjacent the core layer.
 9. The boat hull as claimed in claim 6,further comprising a bulkhead that is integral with the inside of thehull.
 10. The boat hull as claimed in claim 6, further comprising astringer that is integral with the inside of the hull.
 11. The boat hullas claimed in claim 6, wherein the stringer is unitary with the hullbottom.
 12. The boat hull as claimed in claim 6, further comprising astringer and a bulkhead that are unitary with the hull bottom.
 13. Theboat hull as claimed in claim 6, wherein the closed molded process usesvents.
 14. The boat hull as claimed in claim 6, wherein the core is madeof a foaming type material.
 15. The boat hull as claimed in claim 6,wherein the second layer is concave shaped.
 16. The boat hull as claimedin claim 6, wherein one of said layers is concave shaped.
 17. A hullconstructed using a closed mold processes, comprising: a first layer ofcomposite material that is shaped in a concave configuration; a corelayer adjacent to the first layer; a second layer of composite materialthat is shaped in a flat configuration; and at least one stringer formedwith one of said layers.
 18. The hull as claimed in claim 15, whereinthe stringer is integral with the core layer.
 19. The hull as claimed inclaim 15, further comprising a gusset that is formed with one of saidlayers.
 20. The hull as claimed in claim 15, further comprising abulkhead member connected to one of said layers.